Sight glass



p 13, 1939- I w. E JOHNSON 2,155,270

SIGHT cuss Filed Sept 10, 1957 0/1., LEVEL Inventor:

WilFrid E. JO nso'n,

y r His Attor'hey.

man A". 18, 1939 I 2,155,210

UNITED STATES PATENT orrica altar-i sron'r cuss Wilfrid Erlohnson, Fort Wayne. 1nd., aasignor ,to General Electric Company, a corporation of New York Application September 10,1937, Serial No. 163,277

3 Claims. (Cl. 73-831) My invention relates to sight glasses for the moving parts of the compressor housed in the casings of refrigerant compressors, or the like. casing and to observe the height of the oil level The casings of refrigerant compressors are fretherein. The opening it may also be utilized in quently provided with sight glasses in order to charging oil into and draining oil from the eas- 5 allow the operator to observ the moving parts of ing I I. The boss I3 also has a counterbore there- 5 the compressors housed in the casings and the in which provides a shoulder IS in the opening I, lubricant levels within the compressor casings. The sight glass I2 comprises a tubular member In the type of sightglass usually employed, a l8 having a flanged inner end I! which is arglass window is disposed adjacent an observation ranged in the counterbore in the boss I3. The

10 opening in the compressor casing and an arrangeopening in the tubular member I6 is arranged in 10 ment including a packing gland and a follower alignment with and presented to the opening it. nutin threaded engagement with the casingls The flanged inner end I! of the member I6 is provided for retaining the glass window in place, tightly secured to the shoulder l5 about the the packing gland being interposed between the opening it by an arrangement including a tubuglass window and the follower nut. In practice lar follower nut or ring it having a hexagonal 15 this type of sight glass has not been satisfactory head. Preferably, a gasket i9 comprising a copdue to the fact that it is subject to leaks caused per ring covered with lead is interposed between by the deteriorating effect of the lubricant and the shoulder I5 and the flanged inner end I! the refrigerant contained in the compressor casof the member It in order to form a fluid-tight o ing upon the packing gland. Moreover, as the joint therebetween. The inner end of the folcompressor casing is subjected to considerable lower nut I8 directly engages the flanged inner pressure variation during the various operating end I! of the member l6 and the outer surface cycles of the refrigerating machine, the follower of the follower nut I8 is provided with threads nut must exert a. considerable force upon the which engage corresponding threads provided in glass window through the packing gland in order the side wall of the counterbore in the boss I3. 25 to-seal the opening in the compressor casing which A transparent glass window 20 is disposed within often causes the glass window to fracture. the tubular member l5 and extends across the It is an object of my invention to provide an outer end thereof, the marginal edge oi the winimproved sight glass for a compressor casing, or dow 20 being fused to the adjacent portion of the.

the like, which positively seals the casing against tubular member I 6 in order to provide a fluid 30 leaks and which comprises a minimum number tight seal therebetween. Preferably the extreme of parts, outer end of the member I6 is turned inwardly Another object of my invention is to provide adjacent the outer surface of the glass window a sight glass having a glass window which is free 20 as indicatefdat 2| in order to protect the 5 of all strains tending to fracture the same. window 0 against j y incident r p acement Further objects and advantages of my invenand removal. Also the outer end of the follower tion will become apparent as the following denut l8 project Somewhat y d the outer surscription proceeds and the features of novelty face of the window 20 in order to prevent other which characterize my invention will be pointed objects from striking the window 20 and fracout in particular in the claims'appended to and turing the same. 40 forming part of this specification. It will be observed that the follower nut I 8 For a better understanding of my invention has an internal diameter substantially greater reference may be had to the accompanying drawthan the external diameter of the member I6. ing in which Fig. 1 is a side elevational view of a In other words the follower nut l8 surrounds the 5 refrigerant compressor having a casing provided member IS in spaced relation thereto so that the with a sight glass embodying my invention; and window 20 is not strained by the foll'ower nut i8 Fig. 2 is an enlarged sectional view of the sight regardless of the extent to which the follower glass along the line 2-2 of Fig. 1. nut is tightened against the flanged inner end Referring to the drawing, in Fig. lIhave shown I! of the member it. Thus, the seal between 5 a refregrant compressor l0 having a casing II the metal member I 6 and the glass window 20 is. provided with a sight glass l2. As best shown free of strains produced by external forces. In in Fig. 2 the casing II is provided with a boss order to provide a seal between the metal meml3 having an observation opening I therein 'adber i6 and the glass window 20 which is entirely jacent the normal lubricant or oil level in the free of all strains, internal strains in the seal casing, which allows the operator to observe the must also be eliminated. In order to eliminate 55 internal strains in the seal between the metal member 16 and the glass window 20, these parts are formed of materials having thermal expansion characteristics which closely match one another throughout the temperature range between 0 C. and the softening temperature of the glass of the window. This result may be accomplished by forming the member l6 of material comprising an alloy essentially of iron, nickel and cobalt and by forming the window 20 of a material comprising bore-silicate glass, as described in Burger et a1. Patent No. 2,071,196, granted February 16, 1937, and assigned to the General Electric Company, assignee of my present invention.

For example, a glass having the approximate composition of silica (S102), 23% boric oxide (B203), 7% sodium .oxide (NazO), and 5% aluminum oxide (A1203) may be fused to an alloy having the approximate composition of 18% cobalt (Co), 28% nickel (Ni), and 54% iron (Fe) in order to provide a seal therebetween which is free of internal strains. Other examples of suitable glasses and alloys which may be utilized to provide seals free of internal strains are described in the above mentioned Burger et a1. Patent #2,07l,196.

In a seal of this character the glass window 20 does not tend to pull away from the metal member l6 upon cooling after it has been fused thereto. Moreover, the metal member l6 does not tend to crush the glass window 20 upon cooling after the fused seal therebetween has been made. Consequently no internal strains are set up in the seal between the window and the member and a strained-free seal therebetween is provided.

From the foregoing description of the sight glass I2 it will be apparent that the moving parts of the compressor housed within the compressor casing H as well as the oil level in the compressor casing may be readily observed through the'window 20 from the exterior of the casing. Also it will be apparent that the sight glass may be readily placed and removed in a simple manner merely by manipulating the follower nut I8. In view of the fact that the flanged inner end I! of the tubular member I6 is tightly secured to the shoulder l5 and'the window 20 is fused to the member IS, the observation opening ll in the casing II is sealed against leakage of air thereinto and leakage of refrigerant and lubricant therefrom. Moreover, as the glass window 20 of the sight glass is free of all strains tending to cause fracture of the same, breakage is reduced to a minimum.

While I have shown a particular embodiment of my invention in connection with the casing of a refrigerant compressor, I do not desire my invention to be limited to the particular construction shown and described, and I intend in the appended claims to cover all modifications within the scope and spirit of my invention.

What I claim as new and desire to obtain by Letters Patent of the United States is:

1'. A casing having an observation opening therein and a counterbore about one end of said opening, a tubular metal member having a flanged end arranged in said counterbore, means including a follower surrounding said member for tightly securing the flanged end of said member to said casing, and a glass window disposed within said member and sealed thereto.

2. A casing having an observation opening therein, a metal member having a glass window disposed therein and sealed thereto, said member also having an outwardly extending flanged end, and means for clamping said flanged end about said opening and against said casing, said means including a follower ring having an internal diameter substantially greater than the external diameter of said member, whereby strains resulting from clamping said member to said casing are substantially prevented from affecting said window or said seal.

3. A casing having an observation opening therein and a counterbore about one end of said opening, a tubular member having a glass window sealed therein and a flanged end disposed within said counterbore, and a tubular follower surrounding said member in spaced relation thereto and adapted to clamp said flanged end against said casing whereby adverse strains on said window are avoided.

WILFRID E. JOHNSON. 

